| The era of science and technology has accelerated the process of urbanization in our country.Dense high-rise buildings have emerged in many urban areas.The existing mobile communication technology cannot provide high-quality continuous coverage to these areas with dense high-rise buildings.In order to further promote the three-dimensional development of the city,it is urgent to study the three-dimensional space coverage technology to realize the three-dimensional coverage of signals in high-rise densely populated areas.At the same time,the fifth generation mobile communication technology(5G)is developing rapidly,and various new technologies are applied in 5G communication systems,which makes 5G communication have higher data transmission rate,larger network capacity and smaller delay.Among them,3D Multiple Input Multiple Output(MIMO)technology has become one of the most revolutionary technologies in 5G communication.In order to solve the problem of uneven coverage and blind signal area in high-rise buildings,this paper uses beamforming technology and and combines the antenna requirements of 5G communication system to study the building coverage beamforming dual-polarization microstrip antenna array of building coverage for 5G communication system,and achieves the following results:(1)In view of the coverage of dense high-rise buildings in the urban areas,the idea of"three-dimensional space coverage" based on buildings is proposed.Considering a building as a residential area,it is also called a building residential area.According to the height and width of the building,the coverage area of the building district is determined,the height of the building determines the range of beamforming of vertical plane,and the width of the building determines the range of beamforming of horizontal plane.The beamforming methods are studied respectively.For beamforming of vertical plane,a scheme of covering with secant square beamforming is proposed,and the amplitude and phase of each element of antenna array are studied by genetic algorithm.After a series of calculations and optimizations,the eight-element antenna array is finally used to realize the secant square beamforming proposed in this paper,and the excitation distribution of the antenna array element to realize the desired directional pattern is obtained.On this basis,based on the GUI function in MATLAB,the synthesizing software of secant square beamforming antenna array is developed.The development of this software also provides a convenient tool for the promotion and application of secant square beamforming antenna arrays.For beamforming of horizontal plane,the two schemes of loading concave metal baffle and flat top beamforming are respectively adopted to realize the goal that the signal strength received by users of each element is basically the same.(2)A coaxial probe doubly-fed double-layer patch horizontal/vertical dual-polarization antenna element and an one-to-eight unequal power divider feed network are designed.The amplitude and phase of signals at each output port of the feed network meet the requirements of the beamforming antenna array.On this basis,eight element antennas and the feed network are combined to form an eight-element linear array,and concave metal baffles are loaded under the antenna array.Finally,a new dual-polarization microstrip antenna array working in 5G frequency range and applied to building coverage is designed,and the feed network and antenna array system are fabricated and tested.The results show that the working frequency range of the antenna array is 3.4-3.6 GHz,the reflection coefficient of the input port in the frequency range is less than-14dB,the isolation is greater than 30dB,the radiation pattern of pitching plane is approximately secant distribution in the range of 0-40°,and gain from-6dBi to 9dBi,and the gain is less than-10dBi in the range of less than-5° and more than 65°;The amplitude of gain fluctuation in the range of±30° of the radiation pattern of horizontal plane is less than 3.8 dBi,and the gain is less than 0dBi in the range of less than-45°and more than 45°,basically realizing the goal that users of the whole building can basically receive approximately equal signals,while the radiation in other directions is very small,thus effectively radiating energy.(3)The ±45° dual-polarization slot-coupled square microstrip antenna element is designed,and the beamforming of horizontal plane,pitch plane and three-dimensional space of the array antenna are studied.On this basis,the horizon,tal plane of 8-element flat-top beamforming antenna array,the pitch plane of 8-element secant square beamforming antenna array and the three-dimensional space of 8×8 beamforming antenna array are designed respectively.The results show that the 8×8 3D dual-polarization microstrip antenna array proposed and designed in this paper works in 5G frequency rang and is applied to building coverage.the radiation pattern of pitching plane is approximately secant distribution in the range of 0-40°,and gain from-3dBi to 14dBi,and the gain is less than-10dBi in the range of less than-4° and more than 65°;The amplitude of gain fluctuation in the range of±30° of the radiation pattern of horizontal plane is less than 2.5 dBi,and the gain is less than-10dBi in the range of less than-45° and more than 45°,which well realizes the goal that users of the whole building can basically receive approximately equal signals,while the radiation in other directions is very small,thus effectively radiating energy. |
